Please choose your delivery country and your customer group
The effects of the process parameters of shot peening on the microstructural evolution and resulting mechanical property of SUS304 were investigated with microscopic analyses and mechanical tests. Shot peening on SUS304 was carried out with different impact energies and ball diameters (diameter 2.3 - 6 mm). In the deformed layer of 80 - 220 micron with a high dislocation density, the top layer of 30 micron in thickness was found to have nanostructures of 20 - 100 nm with mechanical twins, which decreased with increasing depth. Deformation-induced martensite, whose volume fraction increased as the total energy deposition increased and/or as the ball diameter decreased, even at the same impact energy. The density of the multi-directional mechanical twins gradually decreased and single-directional mechanical twins gradually appeared instead. In addition, the average distance of twins increased with increasing depth in all of the shot-peened specimens. When processed by air blast shot peening, a few M23C6 precipitates were additionally observed on the grain boundaries and are attributed to the conceivably higher temperature reached during the processing.